The present invention relates to an integrated pressure management system that manages pressure and detects leaks in a fuel system. The present invention also relates to an integrated pressure management system that performs a leak diagnostic for the headspace in a fuel tank, a canister that collects volatile fuel vapors from the headspace, a purge valve, and all associated hoses.
In a conventional pressure management system for a vehicle, fuel vapor that escapes from a fuel tank is stored in a canister. If there is a leak in the fuel tank, canister or any other component of the vapor handling system, some fuel vapor could exit through the leak to escape into the atmosphere instead of being stored in the canister. Thus, it is desirable to detect leaks.
In such conventional pressure management systems, excess fuel vapor accumulates immediately after engine shutdown, thereby creating a positive pressure in the fuel vapor management system. Thus, it is desirable to vent, or xe2x80x9cblow-off,xe2x80x9d through the canister, this excess fuel vapor and to facilitate vacuum generation in the fuel vapor management system. Similarly, it is desirable to relieve positive pressure during tank refueling by allowing air to exit the tank at high flow rates. This is commonly referred to as onboard refueling vapor recovery (ORVR).
According to the present invention, a sensor or switch signals that a predetermined pressure exists. In particular, the sensor/switch signals that a predetermined vacuum exists. As it is used herein, xe2x80x9cpressurexe2x80x9d is measured relative to the ambient atmospheric pressure. Thus, positive pressure refers to pressure greater than the ambient atmospheric pressure and negative pressure, or xe2x80x9cvacuum,xe2x80x9d refers to pressure less than the ambient atmospheric pressure.
The present invention is achieved by providing a volatile fuel vapor collection system. This system comprises an integrated pressure management apparatus, a collection canister in fluid communication with the integrated pressure management apparatus; and a connection establishing the fluid communication between the integrated pressure management apparatus and the collection canister. The integrated pressure management apparatus includes a housing defining an interior chamber, the housing including first and second ports communicating with the interior chamber; a pressure operable device separating the chamber into a first portion and a second portion, the first portion communicating with the first port, the second portion communicating with the second port, the pressure operable device permitting fluid communication between the first and second ports in a first configuration and preventing fluid communication between the first and second ports in a second configuration; and a signal chamber in fluid communication with the first portion of the interior chamber, the pressure operable device further separating the signal chamber from the second portion of the interior chamber.
The present invention is also achieved by a method of assembling a volatile fuel vapor collection system. The method comprises providing collection canister having a first one of a male and female members; providing an integrated pressure management apparatus having a second one of the male and female members; and matingly engaging the male and female members with respect to one another. The integrated pressure management apparatus has a pressure operable device separating an interior chamber into a first portion and a second portion, the first portion communicating with the collection canister, the second portion communicating with a vent, the pressure operable device permitting fluid communication between the collection chamber and the vent in a first configuration and preventing fluid communication between the collection chamber and the vent in a second configuration.